Since the Sep. 11, 2001 attacks on the World Trade Center and Pentagon, there has been significant interest in providing enhanced security around buildings and public places. One need is for barriers around buildings and other structures to prevent trucks and other vehicles, perhaps carrying explosives, or just intent upon inflicting damage, from crashing into walls, and so forth. In addition to a need for high-strength barriers of this kind, at the same time, such structures should not be visually offensive, and indeed, it would be beneficial if such barriers were aesthetically appealing, blending into the environment.
One solution is proposed in published U.S. Patent Application No. 2003/0127122, which teaches a flexible blast curtain said to reduce casualties and property damage in the event of a terrorist bombing by intercepting flying debris and dissipating over pressure through deflection of the curtain. The blast curtain may be attached directly to buildings or mounted on frames anchored in close proximity to buildings. The curtain provides complete visibility and easy pedestrian ingress and egress for the buildings.
The curtain is in the form of a flexible barrier which is placed a distance out from the surface to be protected. An impacting missile stretches the barrier until it decelerates to a stop or is deflected. The barrier material has a predetermined tensile strength and stretch that makes it suitable for this application. The known strength and stretch, together with the speed, weight and size of the impacting missile, all of which are given in test requirements, permit design calculation to ascertain barrier deflection at impact. This deflection is a determinate of the minimum distance that this barrier is to be spaced out from the frangible area to be protected.
Published U.S. Patent Application No. 2003/0145534 resides in a large, high-density foam glass tile which can be used as a facade on both exterior and interior building walls. The foam glass tile can also be used with other materials to form a panel or a composite. The invention may be used on the critical surfaces of buildings at high risk for terrorist attacks, in combination with cement, steel or other high strength building materials, and may also be used in surfaces of typical buildings. It purportedly has the advantage of absorbing a substantial portion of a shock wave caused by an explosion, while being more resistant to earthquakes.
According to published U.S. Patent Application No. 2003/0200716, a wall is constructed from precast concrete blocks stacked in tiers in which adjacent blocks are secured together to increase the strength of the wall. Anchors are embedded in the tops of at least some of the blocks. The ends of the blocks have vertical grooves which form a vertical opening when the ends of two blocks abut. The blocks in the tiers are offset so that the openings between blocks in one tier are positioned above the anchors on the blocks on the adjacent lower tier. The blocks in each tier are secured together by a tensioned cable extending through aligned passages in the blocks. Locking members are placed in the openings to secure the ends of the abutting blocks to an anchor in an adjacent lower block.
The window system is fitted with a blast energy absorbing mechanism wherein the support members are formed with at least one arm which at a mounted state of the support frame, extends opposite a corresponding flange associated with the frame, i.e. integral with the frame or otherwise articulated thereto. In accordance with an embodiment of the invention, the flange is a portion of the fixing members adapted for engagement with a corresponding first arm of a support member. In accordance with a further embodiment of the invention the flange is an extension of the frame adapted for engagement with a corresponding second arm of a support member.
A dismantable protective window is disclosed in published U.S. Patent Application No. 20020184839. By one particular embodiment of the invention, the support members are bifurcated elements having a first arm and a second arm, which arms at a mounted state of the support frame, extend opposite a corresponding portion of the fixing members and an extension flange of the frame. The arrangement is such that a shock wave striking the window pane gives rise to generation of forces acting in the plane of the window pane and orthogonally thereto, displacing the support frame in an inward, radial direction, whereby the at least one arm of the support members engage the corresponding flanges.